New Zealand under-20s and Blues wing Tevita Li appeared today in the Manukau District Court, where he admitted exceeding the blood-alcohol limit for someone his age.

His lawyer, Richard Earwacker, asked for a conviction not to be entered and indicated Li, 19, would apply for a discharge without conviction at sentencing next month.

Li was driving in Mangere on May 11 when he was stopped by police.

A blood-alcohol test gave a reading of 45 milligrams of alcohol to 100 millilitres of blood. There is zero alcohol limit for anyone under 20.

Li made his debut for the Blues as an 18-year-old while still a schoolboy at Massey High School when the franchise took on France in June last year and he has played a handful of Super Rugby games this season.

More recently the flying winger starred at the Under-20 World Cup, scoring a hat-trick in New Zealand's pool play loss to South Africa and five tries in the tournament.

Li could not stop the Baby Blacks losing in the semi-final but his performances saw him nominated for the IRB Junior Player of the Year award.

When approached outside court, he refused to comment.

Blues coach Sir John Kirwan said Li had already been disciplined by the franchise and would not face any further action.

"It was done in-house, he was stood down against the Hurricanes," he said. "We see it as a minor misdemeanor, and we'll let the courts take their course now. He's pretty disappointed in himself."